Preparation of 1,3 diamino-2-propanol



Patented Jan. 1, I935 I UNlTED STATES PATENT OFFICE PREPARATION OF 1,3 DIAIVIINO-Z-PROPANOL Robert Roger Bottoms, Louisville, Ky., assignor to The Glrdler Corporation; Louisville, Ky., a corporation of Delaware No Drawing. Application November 23, 1931,

Serial No. 576,952

3 Claims. (Cl. 260-127) In my patents No. 1,783,901, dated December ber 19, 1930, page 1069). The amines produced J7 2,1930 and No. 1,834,016, dated December 1, 1931, by the method therein disclosed contain a. maxi- I have disclosed processes of separating acidic mum of 22% nitrogen, and'in the form of a thick, gases, such as carbon dioxide and/or hydrogen hard, non-,di'stillable gel, while the diaminoproe 6 sulfide, from gaseous mixtures commonly. enpanol made by my process contains about 30% countered in industrial operations, in which nitrogen, is crystalline, and almost completely disgaseous mixtures, said gases occur either as imtillable.

purities or as valuable products to be recovered. In one embodiment of the invention chlorhy- I have discovered that certain amino alcohols drin or epichlorhydrin or other halogenated hy- 10 of relatively high nitrogen content have certain droxyl derivatives are treated with an aqueous 10 important advantagesover any of the compounds solution of ammoniacontaining a fixed alkali, said mentioned in my patents above referredto, but ammonia being employed in quantity many times, so far as I have been able to discover, no satisfor example 5 to 10 times, the' theoretical amount factory process has heretofore been developed, necessary to form the amino derivative desired.

whereby such alcohols may be made economically Aqueous ammonia solutions varying from up 15 and in a comparatively pure state. may be conveniently employed. The aqueous It has been found that organic nitrogen com-' ammonia solution must contain suflicient quantity pounds of a basic nature containing more than of the hydroxide of an alkali metal,-or an alkali of nitrogen and particularly organic comearth metal to combine theoretically with the 20 pounds containing a plurality of amino groups chlorine and form a soluble inorganic salt, the 20 with other basic groups such as the hydroxyl most available alkalifor this purpose being cause group, are particularly adapted for gaseous treattic soda.

ment reactions of the character described. These By using a large excess of ammonia anda fixed compounds are more efiicient per unit volume. alkali, the production, of secondary and tertiary and they permit of substantially complete abamines is almost entirely prevented. The excess 25 sorption and recovery of the acidic gases with ammonia and the amount of free alkali are such smaller temperature diirerences between the ab that the pH of the solution is maintained at a sorption and the recovery steps. Particularly point above 12. The theoretical amount of fixed suitable compounds of this character are diamialkali should be'used for combining with the v nohydroxyl aliphatic compounds, such as normal chlorine liberated from the chlorhydrin, and by 30 diamino propanol. maintaining the pH of the solution above 12 .The main object of my invention is to provide primary amino alcohols may be produced with an a process for the preparation of amino alcohols accompanying production of less than 12% of from relatively inexpensive and readily procursecondary and tertiary amines.

able raw materials, with substantially theoreti- The resulting mixture formed containing the 35 cal yields, and without the formation of large inorganic salt, for example sodium chloride, and quantities of secondary and tertiary amines and the amino derivative may be evaporated to remove other impurities from side reactions. large quantities of the salt by crystallization, and.

In accomplishing this object it has been found, then finally treated with ethyl alcohol to remove 4 that when chlorine or other halogen derivatives the residual salt. The residual amino compound 40 of the alcohol are treated with aqueous or other is in a high state of purity and may be used directsolutions containing large excess of ammonia or ly upon the addition of water for the absorption of its derivatives in the presence of a fixed alkali, acid c gases from gas mixturesthe chlorine or halogen 'of the organic compound As a specific example of one method of preis replaced by an amino group with the resulting paring the high nitrogen content amino v 45 formation of a primary amine. The amine thus tive, p ly P D n 1, the formed is not only in a high state of purity, but following method may be employed: I substantially theoretical yields thereof are obone mo of y l dichloihydrin 129 grams tained, the secondary and tertiary reactions of the is passed into or added to two liters of ammonia amino compounds first formed with the chlorine solution cooled to 30 C. or lower and containing 50 or halogen compounds apparently not taking 20% or more of NH: and two mols of NaOH (80 place at all or taking place to a pr ctlcally negligigrams) This mixture is then stirred for 15 to 20 ble extent. minutes until the reaction is complete, and then Amino alcohols have been made heretofore the ammonia and excess water are distilled ofi.

through the action of aqueous ammonia and Boiling is continued until a large amount of the 5 chlorhydrins. By the processes heretofore emsodium chloride formed has crystallized.

ployed, these amino alcohols have been produced When the crystals of sodium chloride collect to in a low state of purity; Diamino-propanol has a point where they interfere with the boiling, the been produced by Fairbourne andothers (Joursolution is removed and the separated crystals w nal e: the Society of Chemical Industry, neeemfiltered or. Boiling isthen resumed and the sodi-' so um chloride is crystallized until it collects to a point where it again begins to interfere with the boiling, whereupon the solution is again filtered. Practically all the salt can then be removed by crystallization upon boiling under a. vacuum of about 15 to mm., the evaporation being carried out until the temperature of the mixture reaches about 100 C. at which time the sodium chloride and diamine mixture resulting will be practically anhydrous. I

This mixture, while still hot, is then taken up into about two or three times its volume of either methyl or ethyl alcohol (ordinary 95% grade) or isopropyl alcohol, and most of the residual sodium chloride will be precipitated. The precipitate is then filtered away and the alcohol distilled off and recovered. After most of the alcohol has -been distilled 01f, the distillation is continued undera vacuum of about 15 to 25 mm. until the temperature of the mixture reaches about 100 C.

The pure product which may be obtained by distillation of the above crude product under reduced pressure, is a white crystalline solid melting at 42 C. and boiling at about 235 C. and is readily soluble in water in all proportions to form a slightly viscous solution which has a boiling point slightly above 100 C. The distillation will separate the pure product from the final portion of the residual salt and from such polymers as may have been produced.

It is desirable to maintain the ratio of the volume of liquid to chlorhydrin during the reac tion of at least as high as given above, namely, two

' liters per gram mol. of chlorhydrin. A larger proportion of water makes a slightly better prod uct, but the product made as above outlined is entirely satisfactory. It is important to mix the caustic soda or other alkali into the ammonia solution prior to adding the chlorhydrin. The chlorhydrin may be dumped in all at once, or run in slowly provided the liquid is under active agitation at the time the chlorhydrin is added. Clarification by means-of activated charcoal may by employed to give the diamine a somewhat better appearance.

In the method of manufacture as set forth in the above example, the following-equations are thought to represent the approximate course of the reaction when dichlorhydrin is used:

aNH Hun-roam:

aNHs reacts with a molecule of ammonia forming a glyceryl aminochlorhydrin, which immediately reacts with caustic soda forming sodium chloride, releasing water and producing epiaminohydrin. The epiaminohydrin immediately reacts with a further quantity of ammonia producing the diaminopropanol. This reaction with the intermediate formation of epihydrins makes it necessary to have ammonia present in large excess in order to prevent the amino derivatives which are first formed from reacting with further quantities of the chlorhydrin and producing undesirable secondary and tertiary reaction products and other complex polymers.

In the above reaction the ammonia may be replaced in part or whole by ammonia substitution products in which one or more of the hydrogen atoms have been replaced by alkyl aryl or other organic radicals. Other materials than dichlorhydrins, such as glyceromonochlorhydrins, epichlorhydrins, ethylenechlorhydrins and other halohydrins, may be utilized as starting materials to produce the corresponding amino derivatives. Instead of caustic soda, alkali metal carbonates, or alkali earth metal hydroxides, such as those of barium and calcium, may be employed. In all cases the ammonia or its equivalents is preferably used in amounts equivalent to five times or more of that required for the theoretical reaction.

As another example, piperidyl ethanol may be prepared in the following manner. One mol. of ethylene chlorhydrin may be added to an aqueous solution of piperidine and alcohol containing one mol. of piperidine and one mol. of NaOH which has been previously cooled to 510 C. The resulting mixture is stirred until the reaction is com plete. Thereupon the excess water is evaporated as before described, and the residual salt separated by dissolving the free base in alcohol, filtering and distilling oif the alcohol. Other similar heterocyclic nitrogen compounds may also be em ployed instead of piperidine.

In common with the absorbents disclosed in my 'prior patent and application, ,1.3-diamino-2- propanol and other equivalent high nitrogen content basic organic derivatives (which derivatives should preferably be free of carbonyl (C0) and carboxyl (COOH) groups), have the properties of being readily soluble in water or other liq-- ing the absorption stage and also during the heating or gas liberating stage.

These properties permit'the absorption agents in liquid form to be circulated continuously in a closed cycle through the low temperature absorption and higher temperature regeneration stage, with comparatively slight loss of the ab sorbent agent,'ensure long life for the absorbent agent in circulation, enable minimizing of heat consumption through the use of heat interchangers, and the treatment of large volumes of gases for comparatively small volumes of the absorbent.

Also diaminopropanol is not caustic, and therefore is not harmful to use, and may be employed in processing equipment of ordinary materials. It does not reactwlth other gases ordinarily present in the industrial gases to be treated, has no objectionable odor, and does not impart any odor greater part of the acidic gas being driven off at and at high temperatures.

the boiling temperature of the liquid.

The 1,3-diaminopropanol, in addition, may be most advantageously employed as a gas absorbent since relatively weaker solutions thereof will absorb much greater quantities of the acidic gases As a result a much smaller quantity of solution of the diaminopropanol will be circulated to obtain equivalent absorptive capacity, and at much higher tempera- ,tures, for example-at temperatures up to 70 C.

so that when the absorbed acidic gases are liberated a smaller amount of heat is consumed in raising the temperature of the reaction mixture to the boiling point of water or to some other temperature at which the absorbed gas is preferably evolved.

For example, diaminopropanol has been found to have about three times the absorptive capacity of triethan'olamine under the same conditions, a'-

33% solution of diaminopropanol absorbing about 90 volumes of carbon dioxide under usual conditions. While it has been found advantageous to use a 30% to 35% solution of diaminopropanol commercially, any'strength solution may be readiily employed. However, with concentrations greater than 40 to 50% by volume, the diaminopropanol carbonate formed has a tendency to crystallize out especially if the solution is allowed to become cold and stand quietly over a period of several hours. Under these conditions, it has been found most satisfactory to use a smaller concentration.

When a 30 to 35 solution of the diaminopropanol is usedinstead of a 50% solution of triethanolamine, it has been found that the diaminopropanol solution will absorb as much carbon dioxide at a temperature of C. (about 40 volumes of carbon dioxide per volume of liquid solution at atmospheric temperature and pressure) as would be absorbed by the 50% triethanolamine solution at 35 C. In other words, the efficiency of the process inabsorbing carbon dioxide is actually increased with increasing temperature without decreasing the completeness of the removal.

When diaminopropanol is used for absorbing 'hydrogen sulfide it has been found that a 35% solution thereof will absorb twice as much HzS as a 50% solution of triethanolamine.

Although diaminopropanol per se is not a. cyclic compound, it reacts with the water to' form an isopropanol diammonium oxide which is a heterocyclic compound, with carbon, nitrogen and oxygen forming the ring.

Diaminopropanol is a solid at ordinary temperatures, and therefore it is desirable to use it'in water solution. In referring to a water solution of diaminopropanol I desire to have the range so interpreted as to include any compounds which may result from the reaction of diaminopropanol with water or with any of the acidic gases which are or may be absorbed byit.

Due to the fact that diaminopropanol is a much more effective absorbent than the other absorbent previously utilized, it is possible to utilize smaller pumps, pipe lines and heat exchange apparatus. Since the difference of temperature of the absorbent solution between the absorbing and regenerating operation is much smaller than hitherto,

the size of the heat interchanger may be' materially reduced, or in some casm completely eliminated. This is particularly the case where the process is carried out under pressure, as for example, in the case of the absorption and recovery, of carbon dioxide where the partial pres -sure of carbon dioxide is one atmosphere or above.

Any subject matter common to this application .and to my copending application Serial No. 736,-

046, filed July 19, 1934, is broadly claimed in the last mentioned application.

Having thus described my invention, what I claim as new and desire to secure by Letters Patentis: g

I. The process of preparing 1,3-dia-mino-2-prdpanol, which comprises'adding glycerol dichlor- Ihydrin with constant stirring to water containing over 15% of ammonia gas, at a temperature not in excessof 30 C. and also containing the theoretical amount of alkali to combine with the chlorine present in the chlorhydrin to produce.

an alkali metal chloride, there being a large ex cess of ammonia present over and above the theoretical amount required for the reaction; in the order of five to ten times that required by the reaction, the amount of water in the solution being in the ratio of approximately two liters of water per gram mol. of the chlorhydrin.

2. A process of forming 1,3-diamino-2-propa-' nol,v which includes efiecting reaction of 1,3-dichlor-z-propanol with ammonia in the presence of a fixed alkali and water in a sufficient amount so that there will be at least one liter of water for each gram mol. of 1,3-dichlor-2-propanol.

3. A process of preparing 1-3-diamino-2-pro panol, which includes efiecting reaction of 1,3- dichlor-2-propanol with ammonia in the presence of a fixed alkali and of water in an amount equivalent to two liters per gram mol. of the 1,3-dichlor- 2-propanol. v

ROBERT ROGER BO'I'IOMS. 

